Patent Application
20240308685
The present invention concerns a pre-conditioned air (PCA) device for conditioning the air in an interior of a cabin of an aircraft parked on the ground and, at the same time, for sanitizing and possibly disinfecting the air and surfaces in the interior of the cabin. The PCA-device of the present invention is particularly advantageous in that it offers an additional function of sanitizing the air and surfaces inside the cabins of aircraft without changing the routine in application for decades of pre-conditioning the air inside the cabins of aircraft. The pre-conditioned air is treated before being injected into the cabin such as to carry reactive oxygen species (ROS) including dry hydrogen peroxide (DHP) at concentrations compatible with the presence of humans in the cabin during the injection of the thus treated pre-conditioned air. State-of-the-art equipment for injecting the pre-conditioned air can be used in the present invention with a simple and inexpensive modification of the equipment.
When aircraft are parked on the ground, the air inside the cabin needs be conditioned, heated in winter and cooled in summer. When the engines of an aircraft on the ground are off, the energy required for these operations can be provided by the auxiliary power unit (APU) present in most large aircraft. The APU is an auxiliary turbine which is noisy and very expensive to run as it consumes substantial amounts of kerosene with related CO2 emissions.
To reduce CO2 emissions, most international airports are equipped with pre-conditioned air (PCA) devices for conditioning the air in an interior of a cabin of an aircraft parked on the ground with their APU's switched off. Pre-conditioned air systems provide an external supply of conditioned air to cool, ventilate and heat the cabins of parked aircraft. To allow complete switching off the APU, electric power must also be supplied externally. For this reason, many PCA-devices are combined with an AC-electrical power supply typically at 400 Hz. To provide a parked aircraft with conditioned air and with electric power, the APU would be running on average one hour for a narrow-body aircraft and over 1.5 hours for a wide-body aircraft. Having both power and air at the parking location would cut 90% of the APU usage resulting in both less pollution and substantial cost savings.
With the tight schedules on the ground, it becomes difficult for the cleaning teams to properly clean and disinfect all surfaces inside the cabin between the disembarking of the inbound passengers and the embarking of the outbound passengers. With the present crisis of COVID 19, the regulations for sanitizing and disinfecting the interiors of cabins have been tightened drastically. Yet no additional time is granted to the cleaning teams for meeting these new regulations.
In continuation, the term “sanitizing” (and derivatives) refers to lowering the number of germs on a surface to a safe level, according to pre-defined standards. The term “disinfecting” (and derivatives) refers to killing nearly 100 percent of germs on surfaces or objects. Disinfecting is generally slightly stronger than sanitizing. For example, the U.S. Environmental Protection Agency (EPA) sets the levels of germs killing to 99.9% for sanitizing and to 99.999% for disinfecting. While this difference might seem minimal, it can make a substantial difference in reducing the spread of an infection. The term “sterilizing” (and derivatives) refers to destroying or eliminating all forms of microbial life (i.e., 100% of germs). The term “cleaning” (and derivatives) refers to removing dirt and other impurities from a surface. Each of sanitizing, disinfecting, and sterilizing does kill germs but does not necessarily clean dirty surfaces.
Systems have been proposed for sanitizing a seat surface in an aircraft cabin by irradiation of the seat surface with UV-light. For example, EP2772272 describes an autonomous trolley configured for moving along an aisle of an aircraft, with unfolded articulated arms extending over the seats on either side of the aisle. Each arm is equipped with sources of UV-C light oriented towards the seats. Only the seats are treated, not e.g., the overhead stowage bins, and only the seats surfaces exposed to the UV-C light are effectively sanitized. If a magazine lies on a seat, sanitization will be incomplete. The level of sanitization strongly depends on the distance of the surface to be treated from the source of UV-C light. Furthermore, exposure to UV-C light is harmful to human eyesight, Finally, when running, the trolley is on the way of the cleaning teams, disrupting their cleaning routines.
The use of hydrogen peroxide (H2O2) for treating different environments has been described in the art but to our knowledge, never for sanitizing a cabin of a parked aircraft. For example, WO2016176486 describes the use of dry hydrogen peroxide (DHP) for preserving fruits and vegetables enclosed in an enclosed environment such as a restaurant, barn, or the like. US20180192619 describes the use of DHP for sanitizing poultry eggs, chicks, and birds in hatcheries and poultry farms. U.S. Pat. No. 7,354,551 describes a system for decontaminating a room such as a hotel room including a vapour generator which supplies a decontaminant vapour, such as hydrogen peroxide vapour to the room. All these systems, however, require injecting continuously hydrogen peroxide to maintain a constant concentration thereof in the air. This is, however, not possible with an aircraft cabin since the aircraft remains on the ground for a very limited time only during a landing-taking off cycle (on average one hour for a narrow-body aircraft and over 1.5 hours for a wide-body aircraft).
The present invention proposes a solution to the problem of reaching the ever-higher sanitizing and disinfecting standards imposed to airlines, without increasing the short time an aircraft remains parked on the ground within a cycle of disembarking and embarking of passengers, and without disrupting neither the ground operations nor the routine of the cleaning teams during the even shorter time the aircraft is empty of passengers. With the present invention, the passengers and cleaning teams are not even aware that the air and surfaces of the aircraft's cabin are being sanitized as they are cleaning the cabin. These and other advantages of the present invention are presented in continuation.
The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims. In particular, the present invention concerns a pre-conditioned air (PCA-) device for conditioning air in an interior of a cabin of a parked aircraft and for ventilating and sanitizing an air and surfaces in the interior of the cabin, the PCA-device comprising,
The PCA-device comprises a photo catalytic oxidation unit located downstream of the PCA-inlet, preferably at or downstream of the PCA-outlet and intersecting the continuous air pathway, the photo catalytic oxidation unit being configured for producing a peroxided air) by formation of dry hydrogen peroxide at a concentration below 1 ppm in the pre-conditioned air dispensed out of the PCA-outlet, wherein the photo catalytic oxidation unit comprises,
The photo catalytic oxidation unit preferably intersects the pre-conditioned air stream of pre-conditioned air) and is preferably located at or directly adjacent to the PCA-outlet.
In a preferred embodiment, the catalyst is coated on a surface of an air-permeable structure intersecting the continuous air pathway. The air-permeable structure can be formed by a mesh or a grid, both comprising openings, or a series of hollow tubes assembled in a staggered, honeycomb structure defining openings. At least a selection of the openings of the mesh, grid, or hollow tubes is oriented substantially parallel to the continuous air pathway.
The catalyst can be a metal oxide, preferably titanium dioxide or tungsten dioxide, or a mixture of metal oxides including titanium dioxide. The UV-light can have a wavelength comprised between 200 and 400 nm, preferably the UV-light is UV-A light of wavelength comprised between 320 and 400 nm. The dry hydrogen peroxide concentration in the peroxided air (5p) thus produced can be not more than 0.06 ppm, preferably not more than 0.04 ppm, and is at least 0.01 ppm, preferably at least 0.02 ppm. the peroxided air (5p) further comprises reactive oxygen species (ROS) including one or more of •O2 and •OH.
The PCA-unit can either be,
The PCA-unit can be a combined system configured for also supplying alternative current at a frequency of preferably 400 Hz.
The present invention also concerns a method for sanitizing an air and surfaces of an interior of a cabin of a parked aircraft (12) and for conditioning the air in the interior of the cabin, the method comprising,
For a fuller understanding of the nature of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings in which:
The present invention concerns a pre-conditioned air (PCA-) device for conditioning air in an interior of a cabin of a parked aircraft (12) and for sanitizing an air and surfaces in the interior of the cabin. The PCA-device comprises an air pre-conditioning (PCA-) unit (1) and an air distribution ducting (3).
The air pre-conditioning (PCA-) unit (1) comprises,
The air distribution ducting (3) comprises a flexible portion (3f) and may or may not comprise rigid portions (3r), depending on whether the PCA-unit is mobile or fixed. The air distribution ducting extends from a proximal end in fluid communication with the PCA-outlet (10), to a distal end provided with a coupling head (4) configured for being fluidly coupled to an internal air circulation duct of an aircraft. The PCA-device defines a continuous air pathway extending from the PCA-inlet (1i) to the coupling head (4).
The present invention differs from the prior art in that the PCA-device comprises a photo catalytic oxidation unit (2) located anywhere downstream of the PCA-inlet (1i), preferably at or downstream of the PCA-outlet (10). The photo catalytic oxidation unit (2) is positioned such as to intersect the continuous air pathway. The photo catalytic oxidation unit is configured for producing a peroxided air (5p) by formation of dry hydrogen peroxide at a concentration below 1 ppm in the pre-conditioned air (5c) dispensed out of the PCA-outlet.
Dry hydrogen peroxide (DHP) of formula H2O2 is a gas. It is not a vapour from aqueous hydrogen peroxide solutions. DHP behaves like oxygen and nitrogen, diffusing through the air. At concentrations below 1 ppm, DHP is effective for extremely high microbial reduction while being very safe to humans.
As illustrated in
The catalyst is preferably coated on a substrate. The substrate can be air-permeable or not.
Reactive oxygen species (ROS) are chemical molecules with one unpaired electron, formed due to the electron acceptability of O2. ROS are therefore highly reactive. Examples of ROS include peroxides, in particular hydrogen peroxide, superoxide, hydroxyl radical, and the like.
The reduction of molecular oxygen (O2) produces superoxide (•O2−), which is the precursor of most other reactive oxygen species (O2+e−→•O2−). Dismutation of superoxide produces hydrogen peroxide (H2O2)(2H++•O2−+•O2−→H2O2+O2). Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ion and hydroxyl radical (•OH), or fully reduced to water (H2O2+e−→HO−+•OH and 2H++2e−+H2O2→2H2O).
ROS can be produced by photocatalysis, which is a photoreaction accelerated by the presence of a catalyst (2c). In presence of oxygen and water present in the air, the catalyst (2c) creates electron-hole pairs, which generate free radicals (e.g. hydroxyl radicals: •OH and superoxides •O2−) able to undergo secondary reactions.
The catalysts are generally transition metal oxides and semiconductors, as they possess a band gap where no energy level is available to promote recombination of an electron and hole produced by photoactivation in the solid. When a photon with energy equal to or greater than the materials band gap is absorbed by the semiconductor, an electron is excited from the valence band to the conduction band, generating a positive hole in the valence band: MO+hν→MO(h++e−), wherein MO is a metal oxide, h+ and e− are a hole and an electron, and hν is optical energy. Such a photogenerated electron-hole pair is termed an exciton. Upon exposure to oxidants, the excited electrons react to produce reduced products, and upon exposure to reductants, the generated holes react to produce oxidized products at the surface of catalyst (2c) according to the following schemes.
As illustrated in
As shown in
The source of UV-light preferably emits UV-light having a wavelength comprised between 200 and 400 nm. Preferably the UV-light is UV-A light of wavelength comprised between 320 and 400 nm. UV-B or UV-C lights can also be used without danger, since the photo-catalytic unit (2) is enclosed within the PCA-device and people are never exposed to the UV-light. The source of UV-light (2uv) can be a UV-LED (light emitting diode), or a UV-laser, or a UV-fluorescent lamp tube.
The catalyst (2c) is preferably coated on a support.
In a preferred embodiment illustrated in
The air-permeable structure (2p) can form a hollow tubular structure enclosing an elongated source of UV-light (2uv), as illustrated in
As discussed supra the catalyst (2c) is preferably a semiconductor. The catalyst (2c) can be a metal oxide (MO) selected among one or more of the following semiconductors: TiO2, WO2, SnO2, SrTiO2, ZnO, WO3, Fe2O3, Cu2O, CeO2, ZrO2, and the like. Other semiconductors, such as ZnS, CdS, MoS2, or CdSe can be used as catalyst (2c). With a relatively large band gap of 3.2 eV and a UV-spectral region centred around 383 nm, TiO2 (=titanium dioxide or titania) is preferred for its efficient photoactivity and high stability. The semiconductors and, in particular TiO2, can be doped to vary their band gaps and spectral regions and enhance their performance. For example, TiO2 can be doped with one or more of Pt, Au, Ag, Pd, Ru, Rh, In, Li, Na, Mg, Fe, Cr, Ni, Mn, V, Cu, Zn, Co, and the like.
Ambient air (5a) is drawn through the PCA-inlet (1i) into the PCA-unit (1). The ambient air is at ambient temperature (Ta), ambient pressure (Pa), and ambient relative humidity (RHa). The values of Ta, Pa, and RHa depend on the instant meteorological conditions of the location of the PCA-device (day or night, winter or summer, etc.). The ambient air is then filtered through a filtering section (1f) and pre-conditioned in an air-conditioning section (1ac) to extract a pre-conditioned air (5c) at a pre-conditioned temperature (Tc≠Ta) different from the ambient temperature (Ta), at a pre-conditioned pressure (Pc>Pa) greater than the ambient pressure (Pa), and at a pre-conditioned relative humidity (RHc>0) having a positive value. The pre-conditioned temperature (Tc) can be higher than Ta to heat the aircraft cabin, or lower than Ta to cool it. The pre-conditioned pressure (Pc) must be higher than ambient pressure (Pa) to drive the flow of pre-conditioned air (5c) through the air distribution ducting (3) and into the internal air circulation system of the aircraft
The photo catalytic oxidation unit (2) can be located upstream or downstream of the air conditioning section (1ac). As described supra, the photocatalytic formation of ROS relies on the presence of moisture in the air stream being treated. Depending on the location of the photo catalytic oxidation unit (2), the relative humidity (RHa, RHc) of ambient air (5a) or of the pre-conditioned air (5c) must be non-zero. The photo catalytic oxidation unit (2) is preferably positioned downstream of the air conditioning section (1ac) because in case the ambient air is too dry, the air conditioning section can be equipped with a humidifier to raise the moisture content in the air to optimal levels before it reaches the photo catalytic oxidation unit (2).
The ambient air (5a) or the pre-conditioned air (5c) flows through the photo catalytic oxidation unit (2) where under the combined action of the UV-light and the catalyst undergoes photo catalytic reactions with formation of ROS including dry H2O2 (DHP), and other reactive oxygen species such as hydroxyl radicals (•OH) and superoxides (•O2−). This is in contrast with the method described in U.S. Pat. No. 7,354,551 which imposes for safety reasons an empty room during and a time after the sanitization treatment with hydrogen peroxide vapour.
DHP concentrations in the air below 1 ppm are considered as safe for humans. The peroxided air (5p) preferably has a dry hydrogen peroxide concentration of not more than 0.06 ppm, preferably not more than 0.04 ppm, and is at least 0.01 ppm, preferably at least 0.02 ppm. Excellent sanitizing results were observed in aircraft cabins at such ranges of DHP contents, with no danger for any material nor any human being present in the cabin during the injection of peroxided air (5p) into the cabin. This means that sanitization of the cabin can be started before the inbound passengers have left the aircraft, proceed during the cleaning operation by the cleaning team, and end after the outbound passengers have boarded the aircraft, thus maximizing the time available for ventilating and sanitizing the aircraft cabin.
The PCA-device of the present invention can be obtained from a state-of-the-art PCA-device as illustrated in
The PCA-device is preferably a combo device, combining pre-conditioned air and electric power supplies as is well known in the art. The electric power is preferably supplied as alternative current at a frequency of preferably 400 Hz. As shown in
The present invention also concerns a method for ventilating and sanitizing an air and surfaces of an interior of a cabin of a parked aircraft (12) and for conditioning the air in the interior of the cabin. The method comprises the following steps.
The method differs from prior art methods for conditioning the air in an aircraft cabin in that it comprises the following steps,
Optimal ventilation of the cabin can be ensured by 100%-fresh outside air injection, with no or substantially no recirculation of any air in the cabin, contrary to the air conditioning controlled by the APU. This is also by contrast with air conditioning in buildings which generally recirculate a substantial portion of air.
Preliminary tests at an aircraft manufacturer testing facilities have shown excellent results of sanitization of the air and surfaces of a cabin with a DHP concentration lower than 0.06 ppm with treatment times under 60 min. Even hidden surfaces, such as overhead stowage bins and table trays in the upright position were satisfactorily sanitized. This is made possible because DHP is a gas able to diffuse through very small openings. The low DHP concentrations used ([DHP]<0.06 ppm) resulted in a safe exposure for humans. In these times of enhanced awareness to elimination of germs and pathogenic microorganisms, such as the coronavirus, the present invention offers a simple, inexpensive, fast, and safe method for reducing considerably the risks of contamination due to contacts with contaminated surfaces in the interior of an aircraft. With the drop in the number of passengers experienced by all airline companies, and the fear of being contaminated, a recognized sanitization, possibly disinfection of the surfaces and air inside an aircraft cabin is a necessary (not sufficient) condition for restoring the confidence of the public towards flying. The PAC-device of the present invention offers a solution to this challenge.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/054450 | 2/23/2021 | WO |
